Engine starter



Oct. 16, 1951 s, GlLBERT 2,571,230

ENGINE STARTER Filed July 29, 1949 IN VEN TOR.

SAMUEL GILBERT Patented Oct. 16, 1951 UNITED I STATES PATENT OFFICE Samuel Gilbei if ifit i ZTZZ Z L, a'ssignor to Bendix Aviation Corporation; Teterboro, N. J., a corporation of Delaware Application July 29, 1949, Serial N0. 107,550

6 Claims.

The present invention relates to engine starters and particularly to engine starter meshing mechamsm.

In engine starters usually some means are necessary for engaging the starter jaw with the engine to be started. One method used is to frictionally hold the starter jaws to cause axial movement thereof. This method has numerous disadvantages in that the friction means are present during the operation of the starter. Also for very cold starts the friction means are not sufficient to cause the necessary axial movement of the starter jaws,

It is an object of the present invention to provide an improved meshing mechanism that will avoid the above difficulties.

Another object of the invention is to provide an improved starter having high axial torque on the starter jaws during the meshing period.

A further object of the invention is to provide an improved starter.

A further object is to provide an improved starter for operation at low temperatures,

The above and other objects and features of the invention will appear more fully hereinafter from a consideration of the following description taken in connection with the accompanying drawings wherein one embodiment of the invention is illustrated by way of example.

In the drawing the single figure is a sectional view of an engine starter embodying one form of the invention.

Referring to the drawing, the device therein shown comprises a starter assembly including, in general, a motor I having a driving shaft 2 rotatably supported by a bearing 3 mounted in end wall 4 of motor housing 5. A pinion 6, shown as integral with the shaft 2 meshes with planet gears The planet gears I are rotatably supported by ball bearings 8 mounted on stub shafts 9 carried by spider cage It The planet gears I mesh with a ring gear securely fastened against rotation by screws l2, to gear housing I3. The gear housing I3 is secured to the motor housing 5 by screws I4 as shown or by other suitable means.

Integral with the spider cage I is a pinion gear adapted to engage planet gears I6 which also engage the ring gear The gears I6 are supported by bearings I! mounted on stub shafts I8 carried by a drum member I9. The drum member or barrel I9 is rotatably mounted in the housing I3 by hearing 20.

The barrel 9 is connected for the transmission of rotary motion to axially stationary spline nut 2| through a torque limiting disc pack 22. The

disc pack 22 comprises a plurality of friction discs alternately splined to the inner face of the barrel I9 and the outer face of the spline nut 2|. The discs of the pack 22 are forced into frictional engagement with each other by a'plurality of circumferentially spaced springs 23 compressed between a flange 24 on the spline nut 2| and an adjustable nut 25 threaded into the barrel I9 and set so that the disc pack 22 will slip at a predetermined torque.

The long lead internal threads of the spline nut 2| mesh with mating threads of screw shaft 26 which is connected to starter jaw 21 by axial splines 28 for rotation therewith.

The present invention provides novel means for actuating the starter jaw 21 into engagement with a crank shaft 29 or extension thereof of the engine to be started.

The pinion gear I5 has a shaft 30 extending axially therefrom into the barrel I9 and journaled by sleeve bearing 3|. A spur gear 32 is attached to the shaft 30 by a screw 33 or in any other suitable manner. The spur gear 32 meshes with a long splined idler gear 34 supported by an axially projecting inner drum member 35 0f the barrel I9. The drum member 35 has a cutout portion 36 adapted to receive the idler gear 34. The idler gear 34 also meshes with inner clutch discs 31, which form an annulus gear, of the disc pack 38. Outer clutch discs 39 are splined to the screw shaft 26. The discs 31 and 39 are forced into frictional engagement by a helical spring 40 compressed between a plate 4| and aspring retaining ring 42. The retaining ring 42 is held in the screw shaft 26 by a split ring 43 fitted in a groove 44 in the screw shaft 26. The spring 40 forces the discs 37 and 39 against a pressure plate 45 causing the discs to be in frictional engagement with each other.

Torque is transmitted from the spur gear 32 through the idler gear 34 to rotate the screw shaft 26. The splined threads on the screw shaft 26 mesh with the mating threads on the spline nut 2| causing the screw shaft 26 to move axially towards engagement with the crank shaft jaw 29. As the screw shaft 26 moves forward the spring retaining ring 42 moves with the screw shaft 26 and causes the disc pack 38 to slide along the splines of idler gear 34 keeping the pressure plate 45 in contact with a shoulder 46 on the screw shaft 26.

The clutch jaw 21 is retained in operative engagement by a mesh rod 41 fastened to the clutch jaw 2! by a nut 48 and extends into the screw shaft 26. A spring 49 coacts between the clutch jab 21 and screw shaft 26 to effect engagement of the clutch jaw 21. The portion of the rod 41 extending into the screw shaft 26 terminates in a flange 50.

Upon the clutch jaw 21 being engaged, the spring 49 is compressed and a rod securely fastened to the backing plate 4| and extending through the outer disc 39 strikes the flange 50 and removes the spring pressure from the disc pack 38 disengaging the idler gear 34 from the screw shaft 26.

In operation, when the motor I is energized the spur gear 32 will be, for example, rotated in a clockwise direction and torque is transmitted through the idler gear 34 to give counter-clockwise torque to the inner clutch discs 31. The pressure of the spring 40 causes the imier clutch discs 31 to frictionally grip the outer disc 39 transmitting torque to the screw shaft 26. This rotation causes relative rotation of the spiral threads which mate with spiral threads on the spline nut 2| imparting axial movement to the left of the screw shaft 26. This movement of the screw shaft 26 compresses spring 49 which exerts a force upon the clutch jaw 21 to move it into engagement. Upon the clutch jaw 2'l meshing with the engine jaw 29 a slight additional travel of the screw shaft 26 causes the flange 50 on mesh rod 41 to engage the pins 5| and remove the spring pressure on disc pack 38 allowing free rotation of the idler gear 34. Should the clutch jaw 21 abut before full engagement, the spring 49 is compressed by the clutch jaw 21 and the flange 50 on the mesh rod 41 engages the pins 5| to relieve the spring pressure as in full engagement.

Thus a starter embodying the invention has the advantages of a positive drive for engagement yet releasing the drive upon engagement thereby providing higher starter efficiency.

Although only one embodiment of the invention has been illustrated and described, various changes in the form and relative arrangements of the parts, which will now appear to those skilled in the art, may be made without departing from the scope of the invention.

What is claimed is:

1. In an engine starter, the combination of an assembly comprising an axially stationary rotatable nut, a screw shaft in said nut, a starter jaw member adapted for rotation with and axial movement relative to said screw shaft, means including a disc pack for rotating said screw shaft relative to said nut to move said screw shaft axially to said nut to an engine engaging position, means responsive to said engine engaging position to disengage said disc pack.

2. In an engine starter, the combination of an assembly comprising an axially stationary rotatable spline nut, a screw shaft in said nut, a starter jaw member adapted for rotation with and axial movement relative to said screw shaft, a jaw retaining member, spring means interposed between said jaw member and said screw shaft, means including a spring biased disc pack for rotating said screw shaft relative to said spline nut to move said screw shaft axially outward to urge said starter jaw into an operative position, means responsive to said operative position to remove said spring bias from said disc pack to release said first means.

3. In an engine starter, the combination of an assembly comprising an axially stationary rotatable spline nut, a screw shaft in said nut, a starter jaw member adapted for rotation with and axial movement relative to said screw shaft, a jaw retaining member, spring means interposed between said jaw member and said screw shaft, means including a spring biased disc pack for rotating said screw shaft relative to said spline nut to move said screw shaft axially outward to urge said starter jaw into an operative position, means responsive to a predetermined pressure on said starter jaw to remove said spring bias from said disc pack to release said first means.

4. In an engine starter, the combination of an assembly comprising rotatable driving means, an axially stationary rotatable spline nut, a planet gear assembly for connecting said spline nut to said driving means, a screw shaft interposed in said splined nut and having mating splines thereon, a starter jaw member splined to said screw shaft for rotation with and axial movement relative to said screw shaft, a jaw retaining member having a circumferential flange extending into said screw shaft, compression spring means interposed between said jaw member and said screw shaft, a pinion gear rotatably connected to said driving means, an idler gear disposed to mesh with said pinion gear, a friction disc pack, one set of said discs being splined to said idler gear, the other set of said discs being splined to said screw shaft, spring means for biasing said discs into intimate contact, means including said jaw retaining member for removing the bias on said disc when said starter jaw reaches an operative position.

5. In an engine starter comprising, in combination, rotatable driving means, an axially stationary rotatable spline nut, means for connecting said spline nut to said rotatable driving means, a screw shaft in said spline nut and splined thereto, a starter jaw member splined to said screw shaft for rotation with and axial movement relative to said screw shaft, a jaw retaining member extending into and being slidable relative to said screw shaft, a compression spring member interposed between said starter jaw member and said screw shaft, means including an idler gear and a spring biased disc pack splined for axial movement relative to said idler gear for rotating said screw shaft relative to said spline nut for positive axial movement therewith, means responsive to the abutment of said starter jaw to remove said spring bias from said disc pack to release said idler gear thereby to interrupt said positive axial movement.

6. The combination defined by claim 5 in which said last mentioned means includes said jaw retaining member and a pin member cooperating therewith to release said spring biased disc pack.

SAMUEL GILBERT.

No references cited. 

